1. Field of the Invention
The present invention relates to a device for setting a gap between rims in a tire uniformity inspecting machine.
2. Description of the Prior Art
A tire uniformity has been measured with a tire uniformity inspecting machine by mounting a tire to upper and lower spindles through upper and lower rims and pushing a loadwheel to the tire being rotated around the axis of the spindles.
The above-mentioned tire uniformity inspecting machine has such a device as shown in FIG. 4, which can automatically set a gap between the upper and lower rims within the range from L.sub.1 to L.sub.2.
In FIG. 4, upper and lower spindles 1 and 2 are mounted at the end portions of upper and lower supporting shafts 3 and 4 by bolts 5 and 6 so as to be coaxially and vertically opposed to each other, respectively. The upper and lower supporting shafts 3 and 4 are rotatably supported to bearing cases 9 and 10 through bearings 7 and 8, respectively. The upper supporting shaft 3 is rotated around the axis by a drive motor (not shown) while the lower supporting shaft 4 is liftably supported by a lifting means (not shown). The upper spindle 1 has a tapered recessed portion 11 at its lower end while the lower spindle 2 has a tapered projecting portion 12, so that the lower spindle 2, while being lifted, is fitted and connected to the upper spindle 1.
Upper and lower rims 13 and 14 are fitted around the outer circumferences of the upper and lower spindles 1 and 2 so as to be vertically slidable and also removable, and are locked at the suitable positions by upper and lower hydraulically locking means 15 and 16 from the inner circumferential sides thereof, respectively. In addition, FIG. 4 shows the upper and lower rims 13 and 14 whose configurations are different from each other on the right and left sides, and which are vertically changeable between the real line position and the dotted line position, respectively. Accordingly, in this case, the gap between the upper and lower rims 13 and 14 can be suitably set within the range from L.sub.1 to L.sub.2.
The upper and lower hydraulically locking means 15 and 16 include oil chambers 17 and 18 in the inner circumferences thereof, and expansible rings 19 and 20 fitted around the spindles 1 and 2 by nuts 21 and 22, respectively. The oil chambers 17 and 18 are fluidly communicated to oil chambers 25 and 26 located at the center portions of the spindles 1 and 2 through oil passages 23 and 24, respectively. The oil chambers 25 and 26 include rams 29 and 30 of air cylinders 27 and 28, respectively. The air cylinders 27 and 28 include cylinder chambers 31 and 32 formed within the spindles 1 and 2, pistons 33 and 34 slidably fitted within the cylinder chambers 31 and 32, and rams 29 and 30 integrated with the pistons 33 and 34, respectively. The pistons 33 and 34 are energized by springs 35 and 36 to pressurize oils within the oil chambers 25 and 26, respectively. Air chambers 37 and 38 are formed to apply air pressure against the pressing forces of the springs 35 and 36, respectively. The air chambers 37 and 38 are connected from passages 39 and 40 formed in the rams 29 and 30 through a piping 41 and a passage 42 to air sources (not shown), respectively. Accordingly, when air pressures in the air chambers 37 and 38 of the air cylinders 27 and 28 are released, the springs 35 and 36 push the pistons 33 and 34, and rams 29 and 30, to thereby pressurize the oils in the oil chambers 25 and 26, respectively. As a result, the pressures in the oil chambers 17 and 18 are increased to radially outwardly expand the expandable rings 19 and 20 and hence lock the upper and lower rims 13 and 14 from the inner circumferential sides thereof, respectively. In addition, the ram 29 is fitted around the outer circumference of a sleeve 43.
A locking arm 44 is pivotably mounted on the bearing case 9 with a pin 45, and which includes at its lower end an engaging portion 46 detachably engaged with the flange portion of the upper rim 13 and at the upper end an engagement/disengagement operating means connected thereto.
The upper and lower rims 13 and 14 can be locked around the upper and lower spindles 1 and 2 from the inner circumference sides thereof by hydraulically expanding the expandable rings 19 and 20 of the upper and lower hydraulically locking means 15 and 16, respectively. The gap between the upper and lower rims 13 and 14 can be set within the range from L.sub.1 to L.sub.2, to thereby rapidly correspond to the change in tire size.
A test is carried out with use of a tire T applied with compressed air therein for setting the same condition as the real running one. The upper and lower rims 13 and 14 are thus applied with the vertical forces F.sub.1 and F.sub.2, for example, up to 20 tons at maximum in a PC tire, respectively. Accordingly, the locking mechanism depending on only the upper and lower hydraulically locking means 15 and 16 using the expandable rings 19 and 20 is disadvantageous in that the upper and lower rims 13 and 14 tend to slip at the time of applying compressed air into the tire T, thereby causing the rim gap to be changed. For the countermeasure to solve the aforesaid disadvantage, it may be considered to reinforce the fixing forces of respective upper and lower hydraulically locking means 15 and 16. The countermeasure, however, has a limitation in terms of the construction because of the locking mechanism thereof depends on the frictional resistance.